Exam 7: Sampling and Sampling Distributions

From a group of 12 students, we want to select a random sample of 4 students to serve on a university committee. How many different random samples of 4 students can be selected?

Four hundred people were asked whether gun laws should be more stringent. Three hundred said "yes," and 100 said "no." The point estimate of the proportion in the population who will respond "no" is

A department store has determined that 25% of all their sales are credit sales. A random sample of 75 sales is selected. a. What is the probability that the sample proportion will be greater than 0.34? b. What is the probability that the sample proportion will be between 0.196 and 0.354? c. What is the probability that the sample proportion will be less than 0.25? d. What is the probability that the sample proportion will be less than 0.10?

Which of the following is are) point estimators)?

Exhibit 7-1 A random sample of 121 bottles of cologne showed an average content of 4 ounces. It is known that the standard deviation of the contents i.e., of the population) is 0.22 ounces. -Refer to Exhibit 7-1. The standard error of the mean equals

Parameters are

A sample of 25 observations is taken from an infinite population. The sampling distribution of is

An automotive repair shop has determined that the average service time on an automobile is 130 minutes with a standard deviation of 26 minutes. A random sample of 40 automotive services is selected. a. Compute the standard error of the mean. b. What is the probability that the sample of 40 automotive services will have a mean service time greater than 136 minutes? c. Assume the population consists of 400 automotive services. Determine the standard error of the mean.

A population has a mean of 53 and a standard deviation of 21. A sample of 49 observations will be taken. The probability that the sample mean will be greater than 57.95 is

A population of 1,000 students spends an average of $10.50 a day on dinner. The standard deviation of the expenditure is $3. A simple random sample of 64 students is taken. a. What are the expected value, standard deviation, and shape of the sampling distribution of the sample mean? b. What is the probability that these 64 students will spend a combined total of more than $715.21? c. What is the probability that these 64 students will spend a combined total between $703.59 and $728.45?

Cluster sampling is

Whenever the population has a normal probability distribution, the sampling distribution of is a normal probability distribution for

A population consists of 8 items. The number of different simple random samples of size 3 that can be selected from this population is

The following information was collected from a simple random sample of a population. 16 19 18 17 20 18 The point estimate of the mean of the population is

Exhibit 7-3 In a local university, 40% of the students live in the dormitories. A random sample of 80 students is selected for a particular study. -Refer to Exhibit 7-3. The probability that the sample proportion the proportion living in the dormitories) is between 0.30 and 0.50 is

A population has a standard deviation of 16. If a sample of size 64 is selected from this population, what is the probability that the sample mean will be within ± 2 of the population mean?

A random sample of 15 telephone calls in an office showed the duration of each call and whether it was a local or a long distance call. Duration Call Number In Minution Type of Call 1 2 local 2 12 long distance 3 10 local 4 3 local 5 5 long distance 6 6 local 7 3 local 8 5 local 9 8 local 10 4 local 11 5 local 12 4 local 13 5 local 14 4 local 15 9 long distance a. What is the point estimate for the average duration of all calls? b. What is the point estimate for the standard deviation of the population? c. What is the point estimate for the proportion of all calls that were long distance?

A simple random sample of 6 computer programmers in Houston, Texas revealed the sex of the programmers and the following information about their weekly incomes. Programmer Weekly Income Sex A \ 250 M B 270 M C 285 F D 240 M E 255 M F 290 F a. What is the point estimate for the average weekly income of all the computer programmers in Houston? b. What is the point estimate for the standard deviation of the population? c. Determine a point estimate for the proportion of all programmers in Houston who are female.

For a population with any distribution, the form of the sampling distribution of the sample mean is

From a population of 500 elements, a sample of 225 elements is selected. It is known that the variance of the population is 900. The standard error of the mean is approximately